1. Field of the Invention
The present invention relates to a semiconductor device in which a sealing film is formed on the surface of a substrate and a method for manufacturing said device. The present invention is applied, for example, to a semiconductor device which uses the wafer level chip size package method and to a method for manufacturing said device.
2. Description of Related Art
Wafer level chip size package (WCSP) technique is well known as a semiconductor manufacturing technique. WCSP is a technique in which resin sealing is performed before a dicing process.
In WCSP a large number of integrated circuits is formed on the surface of a wafer, and then insulating films comprising protective films, interlayer films and the like are formed on the surface of the wafer so as to expose the center part of each of the electrode pads of these integrated circuits. Next, rewiring (redistribution wiring) patterns are formed on the surface of the exposed face of each pad and on the surface of the interlayer films and, subsequently, bumps are formed on top of this rewiring pattern. The rewiring pattern electrically connects the electrode pads and bumps. Next, a resin sealing film is formed so as to expose the upper ends of these bumps and then external terminals are formed on the upper ends of the bumps.
By using a WCSP technique it is possible to reduce the size of the package and lower manufacturing costs.
In semiconductor devices in which a WCSP technique is employed, one part of the lower surface of the sealing film is in contact with the rewiring pattern and the other part is in contact with the interlayer film. In order to make it more difficult for the sealing film to become detached, it is desirable to increase the size of the contact area between the sealing film and the interlayer film.
However, in contemporary semiconductor devices there tends to be a large number of external terminals. When the number of external terminals increases, the overall area of the rewiring pattern becomes large so that the contact area between the sealing film and the interlayer film is reduced. Therefore, the greater the number of external terminals, the easier it is for the sealing film to become detached.
In addition, in contemporary semiconductor devices there has been a tendency for the chips to become smaller in size. When the chip becomes smaller in size, the contact area between the sealing film and the interlayer film is reduced so that it becomes easier for the sealing film to become detached.
In order to maintain the reliability of semiconductor devices, it is necessary to make it difficult for the sealing film to become detached from the surface of the chip.